[deliverable/linux.git] / arch / avr32 / mm / fault.c

/*
 * Copyright (C) 2004-2006 Atmel Corporation
 *
 * Based on linux/arch/sh/mm/fault.c:
 *   Copyright (C) 1999  Niibe Yutaka
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/mm.h>
#include <linux/module.h>
#include <linux/pagemap.h>
#include <linux/kdebug.h>
#include <linux/kprobes.h>

#include <asm/mmu_context.h>
#include <asm/sysreg.h>
#include <asm/tlb.h>
#include <asm/uaccess.h>

#ifdef CONFIG_KPROBES
static inline int notify_page_fault(struct pt_regs *regs, int trap)
{
	int ret = 0;

	if (!user_mode(regs)) {
		if (kprobe_running() && kprobe_fault_handler(regs, trap))
			ret = 1;
	}

	return ret;
}
#else
static inline int notify_page_fault(struct pt_regs *regs, int trap)
{
	return 0;
}
#endif

int exception_trace = 1;

/*
 * This routine handles page faults. It determines the address and the
 * problem, and then passes it off to one of the appropriate routines.
 *
 * ecr is the Exception Cause Register. Possible values are:
 *   6:  Protection fault (instruction access)
 *   15: Protection fault (read access)
 *   16: Protection fault (write access)
 *   20: Page not found (instruction access)
 *   24: Page not found (read access)
 *   28: Page not found (write access)
 */
asmlinkage void do_page_fault(unsigned long ecr, struct pt_regs *regs)
{
	struct task_struct *tsk;
	struct mm_struct *mm;
	struct vm_area_struct *vma;
	const struct exception_table_entry *fixup;
	unsigned long address;
	unsigned long page;
	long signr;
	int code;
	int fault;
	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;

	if (notify_page_fault(regs, ecr))
		return;

	address = sysreg_read(TLBEAR);

	tsk = current;
	mm = tsk->mm;

	signr = SIGSEGV;
	code = SEGV_MAPERR;

	/*
	 * If we're in an interrupt or have no user context, we must
	 * not take the fault...
	 */
	if (in_atomic() || !mm || regs->sr & SYSREG_BIT(GM))
		goto no_context;

	local_irq_enable();

	if (user_mode(regs))
		flags |= FAULT_FLAG_USER;
retry:
	down_read(&mm->mmap_sem);

	vma = find_vma(mm, address);
	if (!vma)
		goto bad_area;
	if (vma->vm_start <= address)
		goto good_area;
	if (!(vma->vm_flags & VM_GROWSDOWN))
		goto bad_area;
	if (expand_stack(vma, address))
		goto bad_area;

	/*
	 * Ok, we have a good vm_area for this memory access, so we
	 * can handle it...
	 */
good_area:
	code = SEGV_ACCERR;

	switch (ecr) {
	case ECR_PROTECTION_X:
	case ECR_TLB_MISS_X:
		if (!(vma->vm_flags & VM_EXEC))
			goto bad_area;
		break;
	case ECR_PROTECTION_R:
	case ECR_TLB_MISS_R:
		if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)))
			goto bad_area;
		break;
	case ECR_PROTECTION_W:
	case ECR_TLB_MISS_W:
		if (!(vma->vm_flags & VM_WRITE))
			goto bad_area;
		flags |= FAULT_FLAG_WRITE;
		break;
	default:
		panic("Unhandled case %lu in do_page_fault!", ecr);
	}

	/*
	 * If for any reason at all we couldn't handle the fault, make
	 * sure we exit gracefully rather than endlessly redo the
	 * fault.
	 */
	fault = handle_mm_fault(mm, vma, address, flags);

	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
		return;

	if (unlikely(fault & VM_FAULT_ERROR)) {
		if (fault & VM_FAULT_OOM)
			goto out_of_memory;
		else if (fault & VM_FAULT_SIGBUS)
			goto do_sigbus;
		BUG();
	}

	if (flags & FAULT_FLAG_ALLOW_RETRY) {
		if (fault & VM_FAULT_MAJOR)
			tsk->maj_flt++;
		else
			tsk->min_flt++;
		if (fault & VM_FAULT_RETRY) {
			flags &= ~FAULT_FLAG_ALLOW_RETRY;
			flags |= FAULT_FLAG_TRIED;

			/*
			 * No need to up_read(&mm->mmap_sem) as we would have
			 * already released it in __lock_page_or_retry() in
			 * mm/filemap.c.
			 */
			goto retry;
		}
	}

	up_read(&mm->mmap_sem);
	return;

	/*
	 * Something tried to access memory that isn't in our memory
	 * map. Fix it, but check if it's kernel or user first...
	 */
bad_area:
	up_read(&mm->mmap_sem);

	if (user_mode(regs)) {
		if (exception_trace && printk_ratelimit())
			printk("%s%s[%d]: segfault at %08lx pc %08lx "
			       "sp %08lx ecr %lu\n",
			       is_global_init(tsk) ? KERN_EMERG : KERN_INFO,
			       tsk->comm, tsk->pid, address, regs->pc,
			       regs->sp, ecr);
		_exception(SIGSEGV, regs, code, address);
		return;
	}

no_context:
	/* Are we prepared to handle this kernel fault? */
	fixup = search_exception_tables(regs->pc);
	if (fixup) {
		regs->pc = fixup->fixup;
		return;
	}

	/*
	 * Oops. The kernel tried to access some bad page. We'll have
	 * to terminate things with extreme prejudice.
	 */
	if (address < PAGE_SIZE)
		printk(KERN_ALERT
		       "Unable to handle kernel NULL pointer dereference");
	else
		printk(KERN_ALERT
		       "Unable to handle kernel paging request");
	printk(" at virtual address %08lx\n", address);

	page = sysreg_read(PTBR);
	printk(KERN_ALERT "ptbr = %08lx", page);
	if (address >= TASK_SIZE)
		page = (unsigned long)swapper_pg_dir;
	if (page) {
		page = ((unsigned long *)page)[address >> 22];
		printk(" pgd = %08lx", page);
		if (page & _PAGE_PRESENT) {
			page &= PAGE_MASK;
			address &= 0x003ff000;
			page = ((unsigned long *)__va(page))[address >> PAGE_SHIFT];
			printk(" pte = %08lx", page);
		}
	}
	printk("\n");
	die("Kernel access of bad area", regs, signr);
	return;

	/*
	 * We ran out of memory, or some other thing happened to us
	 * that made us unable to handle the page fault gracefully.
	 */
out_of_memory:
	up_read(&mm->mmap_sem);
	if (!user_mode(regs))
		goto no_context;
	pagefault_out_of_memory();
	return;

do_sigbus:
	up_read(&mm->mmap_sem);

	/* Kernel mode? Handle exceptions or die */
	signr = SIGBUS;
	code = BUS_ADRERR;
	if (!user_mode(regs))
		goto no_context;

	if (exception_trace)
		printk("%s%s[%d]: bus error at %08lx pc %08lx "
		       "sp %08lx ecr %lu\n",
		       is_global_init(tsk) ? KERN_EMERG : KERN_INFO,
		       tsk->comm, tsk->pid, address, regs->pc,
		       regs->sp, ecr);

	_exception(SIGBUS, regs, BUS_ADRERR, address);
}

asmlinkage void do_bus_error(unsigned long addr, int write_access,
			     struct pt_regs *regs)
{
	printk(KERN_ALERT
	       "Bus error at physical address 0x%08lx (%s access)\n",
	       addr, write_access ? "write" : "read");
	printk(KERN_INFO "DTLB dump:\n");
	dump_dtlb();
	die("Bus Error", regs, SIGKILL);
}
Commit	Line	Data
5f97f7f9 HS	1	/*
	2	* Copyright (C) 2004-2006 Atmel Corporation
	3	*
	4	* Based on linux/arch/sh/mm/fault.c:
	5	* Copyright (C) 1999 Niibe Yutaka
	6	*
	7	* This program is free software; you can redistribute it and/or modify
	8	* it under the terms of the GNU General Public License version 2 as
	9	* published by the Free Software Foundation.
	10	*/
	11
	12	#include <linux/mm.h>
	13	#include <linux/module.h>
	14	#include <linux/pagemap.h>
1eeb66a1	15	#include <linux/kdebug.h>
9caebec7 CH	16	#include <linux/kprobes.h>
9caebec7 CH	17
5f97f7f9 HS	18	#include <asm/mmu_context.h>
5f97f7f9 HS	19	#include <asm/sysreg.h>
5f97f7f9	20	#include <asm/tlb.h>
623b0355	21	#include <asm/uaccess.h>
5f97f7f9 HS	22
5f97f7f9 HS	23	#ifdef CONFIG_KPROBES
9caebec7	24	static inline int notify_page_fault(struct pt_regs *regs, int trap)
5f97f7f9	25	{
9caebec7	26	int ret = 0;
5f97f7f9	27
9caebec7 CH	28	if (!user_mode(regs)) {
	29	if (kprobe_running() && kprobe_fault_handler(regs, trap))
	30	ret = 1;
	31	}
5f97f7f9	32
9caebec7	33	return ret;
5f97f7f9 HS	34	}
5f97f7f9 HS	35	#else
9caebec7	36	static inline int notify_page_fault(struct pt_regs *regs, int trap)
5f97f7f9	37	{
9caebec7	38	return 0;
5f97f7f9 HS	39	}
	40	#endif
	41
623b0355 HS	42	int exception_trace = 1;
623b0355 HS	43
5f97f7f9 HS	44	/*
	45	* This routine handles page faults. It determines the address and the
	46	* problem, and then passes it off to one of the appropriate routines.
	47	*
	48	* ecr is the Exception Cause Register. Possible values are:
5f97f7f9	49	* 6: Protection fault (instruction access)
623b0355 HS	50	* 15: Protection fault (read access)
	51	* 16: Protection fault (write access)
	52	* 20: Page not found (instruction access)
	53	* 24: Page not found (read access)
	54	* 28: Page not found (write access)
5f97f7f9 HS	55	*/
	56	asmlinkage void do_page_fault(unsigned long ecr, struct pt_regs *regs)
	57	{
	58	struct task_struct *tsk;
	59	struct mm_struct *mm;
	60	struct vm_area_struct *vma;
	61	const struct exception_table_entry *fixup;
	62	unsigned long address;
	63	unsigned long page;
623b0355 HS	64	long signr;
623b0355 HS	65	int code;
83c54070	66	int fault;
bf7c27e9	67	unsigned int flags = FAULT_FLAG_ALLOW_RETRY \| FAULT_FLAG_KILLABLE;
5f97f7f9	68
9caebec7	69	if (notify_page_fault(regs, ecr))
5f97f7f9 HS	70	return;
	71
	72	address = sysreg_read(TLBEAR);
	73
	74	tsk = current;
	75	mm = tsk->mm;
	76
623b0355 HS	77	signr = SIGSEGV;
	78	code = SEGV_MAPERR;
	79
5f97f7f9 HS	80	/*
	81	* If we're in an interrupt or have no user context, we must
	82	* not take the fault...
	83	*/
	84	if (in_atomic() \|\| !mm \|\| regs->sr & SYSREG_BIT(GM))
	85	goto no_context;
	86
	87	local_irq_enable();
	88
759496ba JW	89	if (user_mode(regs))
759496ba JW	90	flags \|= FAULT_FLAG_USER;
bf7c27e9	91	retry:
5f97f7f9 HS	92	down_read(&mm->mmap_sem);
	93
	94	vma = find_vma(mm, address);
	95	if (!vma)
	96	goto bad_area;
	97	if (vma->vm_start <= address)
	98	goto good_area;
	99	if (!(vma->vm_flags & VM_GROWSDOWN))
	100	goto bad_area;
	101	if (expand_stack(vma, address))
	102	goto bad_area;
	103
	104	/*
	105	* Ok, we have a good vm_area for this memory access, so we
	106	* can handle it...
	107	*/
	108	good_area:
623b0355	109	code = SEGV_ACCERR;
623b0355	110
5f97f7f9 HS	111	switch (ecr) {
	112	case ECR_PROTECTION_X:
	113	case ECR_TLB_MISS_X:
	114	if (!(vma->vm_flags & VM_EXEC))
	115	goto bad_area;
	116	break;
	117	case ECR_PROTECTION_R:
	118	case ECR_TLB_MISS_R:
	119	if (!(vma->vm_flags & (VM_READ \| VM_WRITE \| VM_EXEC)))
	120	goto bad_area;
	121	break;
	122	case ECR_PROTECTION_W:
	123	case ECR_TLB_MISS_W:
	124	if (!(vma->vm_flags & VM_WRITE))
	125	goto bad_area;
bf7c27e9	126	flags \|= FAULT_FLAG_WRITE;
5f97f7f9 HS	127	break;
	128	default:
	129	panic("Unhandled case %lu in do_page_fault!", ecr);
	130	}
	131
	132	/*
	133	* If for any reason at all we couldn't handle the fault, make
	134	* sure we exit gracefully rather than endlessly redo the
	135	* fault.
	136	*/
bf7c27e9 KC	137	fault = handle_mm_fault(mm, vma, address, flags);
	138
	139	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
	140	return;
	141
83c54070 NP	142	if (unlikely(fault & VM_FAULT_ERROR)) {
	143	if (fault & VM_FAULT_OOM)
	144	goto out_of_memory;
	145	else if (fault & VM_FAULT_SIGBUS)
	146	goto do_sigbus;
5f97f7f9 HS	147	BUG();
5f97f7f9 HS	148	}
bf7c27e9 KC	149
	150	if (flags & FAULT_FLAG_ALLOW_RETRY) {
	151	if (fault & VM_FAULT_MAJOR)
	152	tsk->maj_flt++;
	153	else
	154	tsk->min_flt++;
	155	if (fault & VM_FAULT_RETRY) {
	156	flags &= ~FAULT_FLAG_ALLOW_RETRY;
45cac65b	157	flags \|= FAULT_FLAG_TRIED;
bf7c27e9 KC	158
	159	/*
	160	* No need to up_read(&mm->mmap_sem) as we would have
	161	* already released it in __lock_page_or_retry() in
	162	* mm/filemap.c.
	163	*/
	164	goto retry;
	165	}
	166	}
5f97f7f9 HS	167
	168	up_read(&mm->mmap_sem);
	169	return;
	170
	171	/*
	172	* Something tried to access memory that isn't in our memory
	173	* map. Fix it, but check if it's kernel or user first...
	174	*/
	175	bad_area:
5f97f7f9 HS	176	up_read(&mm->mmap_sem);
	177
	178	if (user_mode(regs)) {
126187f1	179	if (exception_trace && printk_ratelimit())
623b0355 HS	180	printk("%s%s[%d]: segfault at %08lx pc %08lx "
623b0355 HS	181	"sp %08lx ecr %lu\n",
b460cbc5	182	is_global_init(tsk) ? KERN_EMERG : KERN_INFO,
623b0355 HS	183	tsk->comm, tsk->pid, address, regs->pc,
	184	regs->sp, ecr);
	185	_exception(SIGSEGV, regs, code, address);
5f97f7f9 HS	186	return;
	187	}
	188
	189	no_context:
5f97f7f9 HS	190	/* Are we prepared to handle this kernel fault? */
	191	fixup = search_exception_tables(regs->pc);
	192	if (fixup) {
	193	regs->pc = fixup->fixup;
5f97f7f9 HS	194	return;
	195	}
	196
	197	/*
	198	* Oops. The kernel tried to access some bad page. We'll have
	199	* to terminate things with extreme prejudice.
	200	*/
	201	if (address < PAGE_SIZE)
	202	printk(KERN_ALERT
	203	"Unable to handle kernel NULL pointer dereference");
	204	else
	205	printk(KERN_ALERT
	206	"Unable to handle kernel paging request");
	207	printk(" at virtual address %08lx\n", address);
5f97f7f9 HS	208
	209	page = sysreg_read(PTBR);
	210	printk(KERN_ALERT "ptbr = %08lx", page);
32019828 HS	211	if (address >= TASK_SIZE)
32019828 HS	212	page = (unsigned long)swapper_pg_dir;
5f97f7f9 HS	213	if (page) {
	214	page = ((unsigned long *)page)[address >> 22];
	215	printk(" pgd = %08lx", page);
	216	if (page & _PAGE_PRESENT) {
	217	page &= PAGE_MASK;
	218	address &= 0x003ff000;
	219	page = ((unsigned long *)__va(page))[address >> PAGE_SHIFT];
623b0355	220	printk(" pte = %08lx", page);
5f97f7f9 HS	221	}
5f97f7f9 HS	222	}
623b0355 HS	223	printk("\n");
	224	die("Kernel access of bad area", regs, signr);
	225	return;
5f97f7f9 HS	226
	227	/*
	228	* We ran out of memory, or some other thing happened to us
	229	* that made us unable to handle the page fault gracefully.
	230	*/
	231	out_of_memory:
5f97f7f9	232	up_read(&mm->mmap_sem);
67a8a20f NP	233	if (!user_mode(regs))
67a8a20f NP	234	goto no_context;
87134102	235	pagefault_out_of_memory();
67a8a20f	236	return;
5f97f7f9 HS	237
	238	do_sigbus:
	239	up_read(&mm->mmap_sem);
	240
5f97f7f9	241	/* Kernel mode? Handle exceptions or die */
623b0355 HS	242	signr = SIGBUS;
623b0355 HS	243	code = BUS_ADRERR;
5f97f7f9 HS	244	if (!user_mode(regs))
5f97f7f9 HS	245	goto no_context;
623b0355 HS	246
	247	if (exception_trace)
	248	printk("%s%s[%d]: bus error at %08lx pc %08lx "
	249	"sp %08lx ecr %lu\n",
b460cbc5	250	is_global_init(tsk) ? KERN_EMERG : KERN_INFO,
623b0355 HS	251	tsk->comm, tsk->pid, address, regs->pc,
	252	regs->sp, ecr);
	253
	254	_exception(SIGBUS, regs, BUS_ADRERR, address);
5f97f7f9 HS	255	}
	256
	257	asmlinkage void do_bus_error(unsigned long addr, int write_access,
	258	struct pt_regs *regs)
	259	{
	260	printk(KERN_ALERT
	261	"Bus error at physical address 0x%08lx (%s access)\n",
	262	addr, write_access ? "write" : "read");
	263	printk(KERN_INFO "DTLB dump:\n");
	264	dump_dtlb();
623b0355	265	die("Bus Error", regs, SIGKILL);
5f97f7f9	266	}